Wikipedia has decided to make all links no-follow. This won’t make a shred of difference.
By now, most search marketers realise that any link is potentially valuable. Links are the traffic highways of the web, and Wikipedia is popular, top ten in the serps, so therefore…
Here’s a question: why do people assume that if Wikipedia adds nofollow, then the links won’t count in search engine calculations? It wouldn’t take much for the search engines to make Wikipedia a special case, and ignore the nofollow tag, if that isn’t the case already.
And another: How do people know that Wikipedia was passing any (real) PageRank or authority before? There are many pages which aren’t using the nofollow tag that also aren’t passing any measurable PageRank and/or authority, probably due to some hand tweaking.
The search engines devised nofollow as a means to help defeat comment spam (it didn’t). Now, nofollow has come to mean something else. In Wikipedias case, nofollow is saying to the search engines that Wikipedia doesnt vouch for any link. If Wikipedia or any other reputable domain helps Google to calculate authority, then Google will most likely ignore the nofollow tag.
Smoke and mirrors.
In the end, it doesn’t take much effort or expense to get a link in Wikipedia, so people will continue to do so. I suspect people will still link to Wikipedia for the same reason most people have done so in the past – because they want to point people to information, rather than any thought of reciprocation.